/*
 * Copyright (c) 2011-2013 GoPivotal, Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.nanotek.util.logic;

import java.util.Collection;
import java.util.Map;

/**
 * Assertion utility class that assists in validating arguments. Useful for identifying programmer errors early and
 * clearly at runtime.
 * <p/>
 * <p>For example, if the contract of a public method states it does not allow {@code null} arguments, Assert can be
 * used to validate that contract. Doing this clearly indicates a contract violation when it occurs and protects the
 * class's invariants.
 * <p/>
 * <p>Typically used to validate method arguments rather than configuration properties, to check for cases that are
 * usually programmer errors rather than configuration errors. In contrast to config initialization code, there is
 * usally no point in falling back to defaults in such methods.
 * <p/>
 * <p>This class is similar to JUnit's assertion library. If an argument value is deemed invalid, an {@link
 * IllegalArgumentException} is thrown (typically). For example:
 * <p/>
 * <pre class="code"> Assert.notNull(clazz, "The class must not be null"); Assert.isTrue(i > 0, "The value must be
 * greater than zero");</pre>
 * <p/>
 * Mainly for internal use within the framework; consider Jakarta's Commons Lang >= 2.0 for a more comprehensive suite
 * of assertion utilities.
 *
 * @author Keith Donald
 * @author Juergen Hoeller
 * @author Colin Sampaleanu
 * @author Rob Harrop
 * @since 1.1.2
 */
@SuppressWarnings({"rawtypes"})
public abstract class Assert {

	/**
	 * Assert a boolean expression, throwing {@code IllegalArgumentException} if the test result is {@code false}. <pre
	 * class="code">Assert.isTrue(i &gt; 0, "The value must be greater than zero");</pre>
	 *
	 * @param expression a boolean expression
	 * @param message    the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if expression is {@code false}
	 */
	public static void isTrue(boolean expression, String message) {
		if (!expression) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert a boolean expression, throwing {@code IllegalArgumentException} if the test result is {@code false}. <pre
	 * class="code">Assert.isTrue(i &gt; 0);</pre>
	 *
	 * @param expression a boolean expression
	 * @throws IllegalArgumentException if expression is {@code false}
	 */
	public static void isTrue(boolean expression) {
		isTrue(expression, "[Assertion failed] - this expression must be true");
	}

	/**
	 * Assert that an object is {@code null} . <pre class="code">Assert.isNull(value, "The value must be null");</pre>
	 *
	 * @param object  the object to check
	 * @param message the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if the object is not {@code null}
	 */
	public static void isNull(Object object, String message) {
		if (object != null) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that an object is {@code null} . <pre class="code">Assert.isNull(value);</pre>
	 *
	 * @param object the object to check
	 * @throws IllegalArgumentException if the object is not {@code null}
	 */
	public static void isNull(Object object) {
		isNull(object, "[Assertion failed] - the object argument must be null");
	}

	/**
	 * Assert that an object is not {@code null} . <pre class="code">Assert.notNull(clazz, "The class must not be
	 * null");</pre>
	 *
	 * @param object  the object to check
	 * @param message the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if the object is {@code null}
	 */
	public static void notNull(Object object, String message) {
		if (object == null) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that an object is not {@code null} . <pre class="code">Assert.notNull(clazz);</pre>
	 *
	 * @param object the object to check
	 * @throws IllegalArgumentException if the object is {@code null}
	 */
	public static void notNull(Object object) {
		notNull(object, "[Assertion failed] - this argument is required; it must not be null");
	}

	/**
	 * Assert that the given String is not empty; that is, it must not be {@code null} and not the empty String. <pre
	 * class="code">Assert.hasLength(name, "Name must not be empty");</pre>
	 *
	 * @param text    the String to check
	 * @param message the exception message to use if the assertion fails
	 * @see StringUtils#hasLength
	 */
	public static void hasLength(String text, String message) {
		if (!StringUtils.hasLength(text)) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that the given String is not empty; that is, it must not be {@code null} and not the empty String. <pre
	 * class="code">Assert.hasLength(name);</pre>
	 *
	 * @param text the String to check
	 * @see StringUtils#hasLength
	 */
	public static void hasLength(String text) {
		hasLength(text,
							"[Assertion failed] - this String argument must have length; it must not be null or empty");
	}

	/**
	 * Assert that the given String has valid text content; that is, it must not be {@code null} and must contain at least
	 * one non-whitespace character. <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
	 *
	 * @param text    the String to check
	 * @param message the exception message to use if the assertion fails
	 * @see StringUtils#hasText
	 */
	public static void hasText(String text, String message) {
		if (!StringUtils.hasText(text)) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that the given String has valid text content; that is, it must not be {@code null} and must contain at least
	 * one non-whitespace character. <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre>
	 *
	 * @param text the String to check
	 * @see StringUtils#hasText
	 */
	public static void hasText(String text) {
		hasText(text,
						"[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
	}

	/**
	 * Assert that the given text does not contain the given substring. <pre class="code">Assert.doesNotContain(name,
	 * "rod", "Name must not contain 'rod'");</pre>
	 *
	 * @param textToSearch the text to search
	 * @param substring    the substring to find within the text
	 * @param message      the exception message to use if the assertion fails
	 */
	public static void doesNotContain(String textToSearch, String substring, String message) {
		if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
				textToSearch.contains(substring)) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that the given text does not contain the given substring. <pre class="code">Assert.doesNotContain(name,
	 * "rod");</pre>
	 *
	 * @param textToSearch the text to search
	 * @param substring    the substring to find within the text
	 */
	public static void doesNotContain(String textToSearch, String substring) {
		doesNotContain(textToSearch, substring,
									 "[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
	}


	/**
	 * Assert that an array has elements; that is, it must not be {@code null} and must have at least one element. <pre
	 * class="code">Assert.notEmpty(array, "The array must have elements");</pre>
	 *
	 * @param array   the array to check
	 * @param message the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if the object array is {@code null} or has no elements
	 */
	public static void notEmpty(Object[] array, String message) {
		if (ObjectUtils.isEmpty(array)) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that an array has elements; that is, it must not be {@code null} and must have at least one element. <pre
	 * class="code">Assert.notEmpty(array);</pre>
	 *
	 * @param array the array to check
	 * @throws IllegalArgumentException if the object array is {@code null} or has no elements
	 */
	public static void notEmpty(Object[] array) {
		notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
	}

	/**
	 * Assert that an array has no null elements. Note: Does not complain if the array is empty! <pre
	 * class="code">Assert.noNullElements(array, "The array must have non-null elements");</pre>
	 *
	 * @param array   the array to check
	 * @param message the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if the object array contains a {@code null} element
	 */
	public static void noNullElements(Object[] array, String message) {
		if (array != null) {
			for (Object element : array) {
				if (element == null) {
					throw new IllegalArgumentException(message);
				}
			}
		}
	}

	/**
	 * Assert that an array has no null elements. Note: Does not complain if the array is empty! <pre
	 * class="code">Assert.noNullElements(array);</pre>
	 *
	 * @param array the array to check
	 * @throws IllegalArgumentException if the object array contains a {@code null} element
	 */
	public static void noNullElements(Object[] array) {
		noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
	}

	/**
	 * Assert that a collection has elements; that is, it must not be {@code null} and must have at least one element. <pre
	 * class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
	 *
	 * @param collection the collection to check
	 * @param message    the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if the collection is {@code null} or has no elements
	 */
	public static void notEmpty(Collection collection, String message) {
		if (CollectionUtils.isEmpty(collection)) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that a collection has elements; that is, it must not be {@code null} and must have at least one element. <pre
	 * class="code">Assert.notEmpty(collection, "Collection must have elements");</pre>
	 *
	 * @param collection the collection to check
	 * @throws IllegalArgumentException if the collection is {@code null} or has no elements
	 */
	public static void notEmpty(Collection collection) {
		notEmpty(collection,
						 "[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
	}

	/**
	 * Assert that a Map has entries; that is, it must not be {@code null} and must have at least one entry. <pre
	 * class="code">Assert.notEmpty(map, "Map must have entries");</pre>
	 *
	 * @param map     the map to check
	 * @param message the exception message to use if the assertion fails
	 * @throws IllegalArgumentException if the map is {@code null} or has no entries
	 */
	public static void notEmpty(Map map, String message) {
		if (CollectionUtils.isEmpty(map)) {
			throw new IllegalArgumentException(message);
		}
	}

	/**
	 * Assert that a Map has entries; that is, it must not be {@code null} and must have at least one entry. <pre
	 * class="code">Assert.notEmpty(map);</pre>
	 *
	 * @param map the map to check
	 * @throws IllegalArgumentException if the map is {@code null} or has no entries
	 */
	public static void notEmpty(Map map) {
		notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
	}


	/**
	 * Assert that the provided object is an instance of the provided class. <pre class="code">Assert.instanceOf(Foo.class,
	 * foo);</pre>
	 *
	 * @param clazz the required class
	 * @param obj   the object to check
	 * @throws IllegalArgumentException if the object is not an instance of clazz
	 * @see Class#isInstance
	 */
	public static void isInstanceOf(Class<?> clazz, Object obj) {
		isInstanceOf(clazz, obj, "");
	}

	/**
	 * Assert that the provided object is an instance of the provided class. <pre class="code">Assert.instanceOf(Foo.class,
	 * foo);</pre>
	 *
	 * @param type    the type to check against
	 * @param obj     the object to check
	 * @param message a message which will be prepended to the message produced by the function itself, and which may be
	 *                used to provide context. It should normally end in a ": " or ". " so that the function generate
	 *                message looks ok when prepended to it.
	 * @throws IllegalArgumentException if the object is not an instance of clazz
	 * @see Class#isInstance
	 */
	public static void isInstanceOf(Class<?> type, Object obj, String message) {
		notNull(type, "Type to check against must not be null");
		if (!type.isInstance(obj)) {
			throw new IllegalArgumentException(
					(StringUtils.hasLength(message) ? message + " " : "") +
							"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
							"] must be an instance of " + type);
		}
	}

	/**
	 * Assert that {@code superType.isAssignableFrom(subType)} is {@code true}. <pre class="code">Assert.isAssignable(Number.class,
	 * myClass);</pre>
	 *
	 * @param superType the super type to check
	 * @param subType   the sub type to check
	 * @throws IllegalArgumentException if the classes are not assignable
	 */
	public static void isAssignable(Class<?> superType, Class<?> subType) {
		isAssignable(superType, subType, "");
	}

	/**
	 * Assert that {@code superType.isAssignableFrom(subType)} is {@code true}. <pre class="code">Assert.isAssignable(Number.class,
	 * myClass);</pre>
	 *
	 * @param superType the super type to check against
	 * @param subType   the sub type to check
	 * @param message   a message which will be prepended to the message produced by the function itself, and which may be
	 *                  used to provide context. It should normally end in a ": " or ". " so that the function generate
	 *                  message looks ok when prepended to it.
	 * @throws IllegalArgumentException if the classes are not assignable
	 */
	public static void isAssignable(Class<?> superType, Class<?> subType, String message) {
		notNull(superType, "Type to check against must not be null");
		if (subType == null || !superType.isAssignableFrom(subType)) {
			throw new IllegalArgumentException(message + subType + " is not assignable to " + superType);
		}
	}


	/**
	 * Assert a boolean expression, throwing {@code IllegalStateException} if the test result is {@code false}. Call isTrue
	 * if you wish to throw IllegalArgumentException on an assertion failure. <pre class="code">Assert.state(id == null,
	 * "The id property must not already be initialized");</pre>
	 *
	 * @param expression a boolean expression
	 * @param message    the exception message to use if the assertion fails
	 * @throws IllegalStateException if expression is {@code false}
	 */
	public static void state(boolean expression, String message) {
		if (!expression) {
			throw new IllegalStateException(message);
		}
	}

	/**
	 * Assert a boolean expression, throwing {@link IllegalStateException} if the test result is {@code false}. <p>Call
	 * {@link #isTrue(boolean)} if you wish to throw {@link IllegalArgumentException} on an assertion failure. <pre
	 * class="code">Assert.state(id == null);</pre>
	 *
	 * @param expression a boolean expression
	 * @throws IllegalStateException if the supplied expression is {@code false}
	 */
	public static void state(boolean expression) {
		state(expression, "[Assertion failed] - this state invariant must be true");
	}

}
